When internal combustion engines are started, generally the position of the shafts, in particular the crankshaft of the internal combustion engine, but also possibly the camshaft, is not known. Correspondingly, an efficient engine controlling of the internal combustion engine in a motor vehicle can usually begin only after a few rotations of the engine.
This deficit is one of the main causes of the fact that the emission of pollutants from the internal combustion engine is significantly higher during the starting than during later operating phases of the engine.
Conventionally, it has therefore usually been attempted to recognize the position of the crankshaft and/or camshaft during the process of starting up the internal combustion engine. This takes place for example via what are known as encoders, for example encoder wheels, which are provided with a number of teeth on their circumference. From determined gaps in these toothed edges, the position of the shaft can be recognized during starting. During the shutoff process, via a runout recognition the attempt can be made to continue to follow the position of the engine until it comes to a standstill. During standstill, in contrast, any change in the engine can no longer be detected.
Various types of sensors are available that are suitable for acquiring the angular position of a crankshaft and/or camshaft. For example, German Patent Application No. DE 103 38 120 A1 describes a magnetic multiple encoder that can be used in particular to measure the angular position of a crankshaft of a motor vehicle. The multiple encoder has a magnetic track having a strip-shaped magnetization with alternating polarity, and at least one marking segment for defining a reference position. The marking segment is fashioned in such a way that it comprises a center area that is not magnetized or is only weakly magnetized, as well as two strips that are magnetized with the same polarity and are situated on either side of the center area.
However, generally the conventional sensor systems have many disadvantages. In particular, one disadvantage is that many of these sensors cannot recognize the engine position immediately when the internal combustion engine is started, but rather only when particular markings (for example the marking segment described in German Patent Application No. DE 103 38 120 A1) pass a corresponding sensor.
In addition, conventional systems are often sensitive to the high thermal loads that can occur in internal combustion engines during operation. In addition, in many cases the sensor systems take up a very large amount of space, and require an expensive energy supply. Due to the limited space conditions in particular in the area of the cylinder heads of internal combustion engines, this increased space requirement of sensors of this type is in many cases not acceptable.